MySQL Reference Manual :: 23 Precision Math

The introduction of new SQL modes in MySQL 5.0.2 that control how strict the server is about accepting or rejecting invalid data.

The introduction in MySQL 5.0.3 of a library for fixed-point arithmetic.

More precise calculations.

For exact-value numbers, calculations do not introduce floating-point error. Instead, exact precision is used. For example, a number such as .0001 is treated as an exact value rather than as an approximate value, and summing it 10,000 times produces a result of 1, not a value "close" to 1.

Well-defined rounding behavior.

For the exact-value numbers, the result of ROUND() depends on its argument, not on factors such as how the underlying C library works.

Improved platform independence.

Operations on exact numeric values are the same across different platforms such as Windows and Unix.

Control over invalid value handling.

Overflow and division by zero are detectable and can be treated as errors. For example, you can treat a value that is too large for a column as an error rather than having the value truncated to lie within the range of the column's data type. Similarly, you can treat division by zero as an error rather than as an operation that produces a result of NULL. The choice of which approach to take is determined by the setting of the sql_mode system variable.